Eobeet e



(NoModeL) R. E. L. HOLMES.

DEVICE FOR OVER'GOMING DEAD CENTERS. No. 351,323. Trg Patented Oct. 19, 1886.

anvmtoz N. PUERS, PMlwLi hi n nn n. u. c.

UNITED STATES PATENT Fries.

ROBERT E. L. HOLMES, OF ST. LOUIS, MISSOURI, ASSIG-NOR OF ONE-HALF TO SYLVESTER T. JOHNSTON, OF SAME PLACE.

DEVICE FOR OVERCOMING DEAD -CENTERS.

SPECIFICATION forming part of Letters Patent No. 351,323, dated October 19, 1886.

Application filed May 27, 1856.

T aZl whom, it may concern.-

Be it known that I, ROBERT-E. L. HoLMEs, a citizen of the -U-nited States, residing at St. Louis, in the State of Missouri, have invented a new and useful Improvement in Overcoming Dead-Centers in \Vorking Sewing-Machines, which of the following is a specification.

My invention relates to an improvement in that class of mechanical devices designed to overcome dead-centers, and to be used more especiallyin preventing the fly-wheels of sewing-machines from stopping on their centers and rotating in the wrong direction; and it consists in the peculiar construction and coin bination of devices that will be more fully set forth hereinafter, and particularly pointed out in the claim.

The object of myinvention is to provide a spring attachment to keep the fly-wheel from stopping on the dead-center.

In the drawings, Figure l is an elevation of parts of a sewing-machine provided with my improvements. Fig. 2 is diagram illustrating a modification.

A represents the frame of a sewingmachine table, and B represents the top.

0 is the fly-wheel; D, the treadle, and E the pitman connecting the treadle with the flywheel.

F represents a pair of bearing-blocks, one of which is secured to the under side of the top B onthe rear side thereof, and the other is attached to the upper end of the pitman E or to the fly-wheel O, or to the crank-pin.

G represents acoiled spring having only one coil or convolution, the ends of said spring being turned outwardly and extending from opposite sides of the circular portion of the spring and in line with each other, as shown. The upper end of the spring is bent andpivoted in the upper bearing-block F, and the lower end of the spring is pivoted in the bearing-bloek attached to the pitman. The fly-wheel, pitman, and treadle are in their normal positions, as shown in solid lines in Fig. 1. \Vhen the treadle is operated to rotate the fly-wheel, the

A coil of the spring is first compressed, as indicated in dotted lines in Fig. l, and then distended as the crank-pin sweeps around the cen- Serial No. 203,454. (No model.)

ter of the wheel. It will be noticed that the lower bearing-block F is secured on one side of the pitman E at a considerable distance from the center of the crank-pin, and as the lower extending arm or end of the coiled spring is pivoted to the said block, it will be readily understood that when the spring is compressed or extended at either point of the dead-center, that it exerts a pressure on the upper end of the pitman-rod out of line with the center, of the crank-pin, and thus effectually prevents the wheel from coming to a standstill on the i dead-center, thus insuring the easy and con- 'tinuous rotation of the fly-wheel at the will of the operator.

In Fig- 2 I illustrate a modified form of my invention, in which, instead of providing the spring with a circular coil, I bend it so as to form an open loop, forming a semicircle, G, extending from each side of the spring, thereby effecting the same result as set forth. in the foregoing description.

I am aware that it is broadly old to employ a spring to assist in overcoming dead-centers in treadle-working machines; but in each instance of such application the construction of the spring has been different from what I claim.

In my spring attachment the spring has one or more coils or convolutions, which are preferably arranged in a vertical plane, and when drawn upon are wound and unwound like the spring of an ordinary clock. It is the automatic unwinding of this spring that causes the deacl-center to be passed or overcome. As the spring is being constantly wound by the action of the treadle, it is readily seen that it will not lose its tension, as would be the case with a plain spiral spring in which the coils are being constantly distended. The improvement over such a spring is manifest without further explanation.

I am aware tliatit is old to employ a spring attachment in which the attaching points of the springs are pivoted and thus caused to oscillate.

I am also aware thatitis broadly old to employ 5 a spring having two or more coils,one of which expands while the other contracts, and vice versa. In my invention,whether I use one or two coils for the spring, said coils expand together, and in addition to. this I mount the ends of the spring in pivotal bearings, causing the spring not only to expand and contract, but also to move with the pitman in turning the dead-center; My claim therefore resides in the combination of these two features, enabling the spring to move with the pitman in its circular path, the coil or coils of the spring being contractedin the movement, and at the proper time the coils being automatically unwound and overeomingthe deadcenter. Another point of difference over spring attachments of this class resides in the fact that the two pivotal ends of the spring are arranged diametrically opposite each other, so that the action of Windingisbroughtto bear in straight lines, allowing an even and regular action unaccompanied by any sudden jerks, which would be injurious both to the operator and the machine.

Having thus described my invention, I claim 1 The herein-described attachment to sewingmachines and the like, comprising-the spring G, having one or more coils or convolutions to be wound and unwound, one end of the spring being pivoted to a fixed part of the machine, while the other endis pivoted preferably to the pitman out of line with the crank-pin, the 0 two ends of the spring being diametrically opposite each other, as set forth.

'In testimony thatl claim the foregoing as my own I have hereto affixed my signature in presence of two witnesses.

ROBERT E. L. HOLMES.

WVitnesses:

OHAs. AQ lWIAeEn, C. D. GREENE, Jr. 

